/** Perform the second (server-side) step of a circuit-creation handshake of
* type <b>type</b>, responding to the client request in <b>onion_skin</b>
* using the keys in <b>keys</b>. On success, write our response into
* <b>reply_out</b>, generate <b>keys_out_len</b> bytes worth of key material
* in <b>keys_out_len</b>, a hidden service nonce to <b>rend_nonce_out</b>,
* and return the length of the reply. On failure, return -1.
*/
int
onion_skin_server_handshake(int type,
const uint8_t *onion_skin, size_t onionskin_len,
const server_onion_keys_t *keys,
uint8_t *reply_out,
uint8_t *keys_out, size_t keys_out_len,
uint8_t *rend_nonce_out)
{
int r = -1;
switch (type) {
case ONION_HANDSHAKE_TYPE_TAP:
if (onionskin_len != TAP_ONIONSKIN_CHALLENGE_LEN)
return -1;
if (onion_skin_TAP_server_handshake((const char*)onion_skin,
keys->onion_key, keys->last_onion_key,
(char*)reply_out,
(char*)keys_out, keys_out_len)<0)
return -1;
r = TAP_ONIONSKIN_REPLY_LEN;
memcpy(rend_nonce_out, reply_out+DH_KEY_LEN, DIGEST_LEN);
break;
case ONION_HANDSHAKE_TYPE_FAST:
if (onionskin_len != CREATE_FAST_LEN)
return -1;
if (fast_server_handshake(onion_skin, reply_out, keys_out, keys_out_len)<0)
return -1;
r = CREATED_FAST_LEN;
memcpy(rend_nonce_out, reply_out+DIGEST_LEN, DIGEST_LEN);
break;
case ONION_HANDSHAKE_TYPE_NTOR:
if (onionskin_len < NTOR_ONIONSKIN_LEN)
return -1;
{
size_t keys_tmp_len = keys_out_len + DIGEST_LEN;
uint8_t *keys_tmp = tor_malloc(keys_out_len + DIGEST_LEN);
if (onion_skin_ntor_server_handshake(
onion_skin, keys->curve25519_key_map,
keys->junk_keypair,
keys->my_identity,
reply_out, keys_tmp, keys_tmp_len)<0) {
tor_free(keys_tmp);
return -1;
}
memcpy(keys_out, keys_tmp, keys_out_len);
memcpy(rend_nonce_out, keys_tmp+keys_out_len, DIGEST_LEN);
memwipe(keys_tmp, 0, keys_tmp_len);
tor_free(keys_tmp);
r = NTOR_REPLY_LEN;
}
break;
default:
log_warn(LD_BUG, "called with unknown handshake state type %d", type);
tor_fragile_assert();
return -1;
}
return r;
}
/** Run unit tests for the onion handshake code. */
static void
test_onion_handshake(void *arg)
{
/* client-side */
crypto_dh_t *c_dh = NULL;
char c_buf[TAP_ONIONSKIN_CHALLENGE_LEN];
char c_keys[40];
/* server-side */
char s_buf[TAP_ONIONSKIN_REPLY_LEN];
char s_keys[40];
int i;
/* shared */
crypto_pk_t *pk = NULL, *pk2 = NULL;
(void)arg;
pk = pk_generate(0);
pk2 = pk_generate(1);
/* client handshake 1. */
memset(c_buf, 0, TAP_ONIONSKIN_CHALLENGE_LEN);
tt_assert(! onion_skin_TAP_create(pk, &c_dh, c_buf));
for (i = 1; i <= 3; ++i) {
crypto_pk_t *k1, *k2;
if (i==1) {
/* server handshake: only one key known. */
k1 = pk; k2 = NULL;
} else if (i==2) {
/* server handshake: try the right key first. */
k1 = pk; k2 = pk2;
} else {
/* server handshake: try the right key second. */
k1 = pk2; k2 = pk;
}
memset(s_buf, 0, TAP_ONIONSKIN_REPLY_LEN);
memset(s_keys, 0, 40);
tt_assert(! onion_skin_TAP_server_handshake(c_buf, k1, k2,
s_buf, s_keys, 40));
/* client handshake 2 */
memset(c_keys, 0, 40);
tt_assert(! onion_skin_TAP_client_handshake(c_dh, s_buf, c_keys,
40, NULL));
tt_mem_op(c_keys,OP_EQ, s_keys, 40);
memset(s_buf, 0, 40);
tt_mem_op(c_keys,OP_NE, s_buf, 40);
}
done:
crypto_dh_free(c_dh);
crypto_pk_free(pk);
crypto_pk_free(pk2);
}
static void
bench_onion_TAP(void)
{
const int iters = 1<<9;
int i;
crypto_pk_t *key, *key2;
uint64_t start, end;
char os[TAP_ONIONSKIN_CHALLENGE_LEN];
char or[TAP_ONIONSKIN_REPLY_LEN];
crypto_dh_t *dh_out;
key = crypto_pk_new();
key2 = crypto_pk_new();
if (crypto_pk_generate_key_with_bits(key, 1024) < 0)
goto done;
if (crypto_pk_generate_key_with_bits(key2, 1024) < 0)
goto done;
reset_perftime();
start = perftime();
for (i = 0; i < iters; ++i) {
onion_skin_TAP_create(key, &dh_out, os);
crypto_dh_free(dh_out);
}
end = perftime();
printf("Client-side, part 1: %f usec.\n", NANOCOUNT(start, end, iters)/1e3);
onion_skin_TAP_create(key, &dh_out, os);
start = perftime();
for (i = 0; i < iters; ++i) {
char key_out[CPATH_KEY_MATERIAL_LEN];
onion_skin_TAP_server_handshake(os, key, NULL, or,
key_out, sizeof(key_out));
}
end = perftime();
printf("Server-side, key guessed right: %f usec\n",
NANOCOUNT(start, end, iters)/1e3);
start = perftime();
for (i = 0; i < iters; ++i) {
char key_out[CPATH_KEY_MATERIAL_LEN];
onion_skin_TAP_server_handshake(os, key2, key, or,
key_out, sizeof(key_out));
}
end = perftime();
printf("Server-side, key guessed wrong: %f usec.\n",
NANOCOUNT(start, end, iters)/1e3);
start = perftime();
for (i = 0; i < iters; ++i) {
crypto_dh_t *dh;
char key_out[CPATH_KEY_MATERIAL_LEN];
int s;
dh = crypto_dh_dup(dh_out);
s = onion_skin_TAP_client_handshake(dh, or, key_out, sizeof(key_out),
NULL);
crypto_dh_free(dh);
tor_assert(s == 0);
}
end = perftime();
printf("Client-side, part 2: %f usec.\n",
NANOCOUNT(start, end, iters)/1e3);
done:
crypto_pk_free(key);
crypto_pk_free(key2);
}
static void
test_bad_onion_handshake(void *arg)
{
char junk_buf[TAP_ONIONSKIN_CHALLENGE_LEN];
char junk_buf2[TAP_ONIONSKIN_CHALLENGE_LEN];
/* client-side */
crypto_dh_t *c_dh = NULL;
char c_buf[TAP_ONIONSKIN_CHALLENGE_LEN];
char c_keys[40];
/* server-side */
char s_buf[TAP_ONIONSKIN_REPLY_LEN];
char s_keys[40];
/* shared */
crypto_pk_t *pk = NULL, *pk2 = NULL;
(void)arg;
pk = pk_generate(0);
pk2 = pk_generate(1);
/* Server: Case 1: the encrypted data is degenerate. */
memset(junk_buf, 0, sizeof(junk_buf));
crypto_pk_obsolete_public_hybrid_encrypt(pk,
junk_buf2, TAP_ONIONSKIN_CHALLENGE_LEN,
junk_buf, DH_KEY_LEN, PK_PKCS1_OAEP_PADDING, 1);
tt_int_op(-1, OP_EQ,
onion_skin_TAP_server_handshake(junk_buf2, pk, NULL,
s_buf, s_keys, 40));
/* Server: Case 2: the encrypted data is not long enough. */
memset(junk_buf, 0, sizeof(junk_buf));
memset(junk_buf2, 0, sizeof(junk_buf2));
crypto_pk_public_encrypt(pk, junk_buf2, sizeof(junk_buf2),
junk_buf, 48, PK_PKCS1_OAEP_PADDING);
tt_int_op(-1, OP_EQ,
onion_skin_TAP_server_handshake(junk_buf2, pk, NULL,
s_buf, s_keys, 40));
/* client handshake 1: do it straight. */
memset(c_buf, 0, TAP_ONIONSKIN_CHALLENGE_LEN);
tt_assert(! onion_skin_TAP_create(pk, &c_dh, c_buf));
/* Server: Case 3: we just don't have the right key. */
tt_int_op(-1, OP_EQ,
onion_skin_TAP_server_handshake(c_buf, pk2, NULL,
s_buf, s_keys, 40));
/* Server: Case 4: The RSA-encrypted portion is corrupt. */
c_buf[64] ^= 33;
tt_int_op(-1, OP_EQ,
onion_skin_TAP_server_handshake(c_buf, pk, NULL,
s_buf, s_keys, 40));
c_buf[64] ^= 33;
/* (Let the server procede) */
tt_int_op(0, OP_EQ,
onion_skin_TAP_server_handshake(c_buf, pk, NULL,
s_buf, s_keys, 40));
/* Client: Case 1: The server sent back junk. */
const char *msg = NULL;
s_buf[64] ^= 33;
tt_int_op(-1, OP_EQ,
onion_skin_TAP_client_handshake(c_dh, s_buf, c_keys, 40, &msg));
s_buf[64] ^= 33;
tt_str_op(msg, OP_EQ, "Digest DOES NOT MATCH on onion handshake. "
"Bug or attack.");
/* Let the client finish; make sure it can. */
msg = NULL;
tt_int_op(0, OP_EQ,
onion_skin_TAP_client_handshake(c_dh, s_buf, c_keys, 40, &msg));
tt_mem_op(s_keys,OP_EQ, c_keys, 40);
tt_ptr_op(msg, OP_EQ, NULL);
/* Client: Case 2: The server sent back a degenerate DH. */
memset(s_buf, 0, sizeof(s_buf));
tt_int_op(-1, OP_EQ,
onion_skin_TAP_client_handshake(c_dh, s_buf, c_keys, 40, &msg));
tt_str_op(msg, OP_EQ, "DH computation failed.");
done:
crypto_dh_free(c_dh);
crypto_pk_free(pk);
crypto_pk_free(pk2);
}
